Is it possible to password-protect your bitcoin wallet? If not I'm a bit concerned that someone with access to my computer could steal my beloved bitcoins.

Congrats on an excellent and important project, BTW.

Every time a block is mined, a certain amount of BTC (called the
subsidy) is created out of thin air and given to the miner. The
subsidy halves every four years and will reach 0 in about 130 years.Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here.

Ah, just remember that the software won't automatically know how to decrypt it. If you want to always keep the wallet.dat used by the client encrypted, you'll need some sort of script to decrypt it before launching the client.

The best approach to protect your bitcoins is to transfer the amount that you want to "keep safe" to a new wallet, encrypt and back up this wallet on off line medias and maybe on a remote server. And don't forget to back up your encryption keys too.